diff --git a/activesupport/lib/active_support/core_ext/object/extending.rb b/activesupport/lib/active_support/core_ext/object/extending.rb
index de8121f274b27215e827e43c0ff2ce906a5dcd70..7ac13d3d1aac4c106af99aa96c6b98d9933126ab 100644
--- a/activesupport/lib/active_support/core_ext/object/extending.rb
+++ b/activesupport/lib/active_support/core_ext/object/extending.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/class/removal'
+
 class Class
   # Rubinius
   if defined?(Class.__subclasses__)